Bodybuilding legend Arnold Schwarzenegger is taking another look at weight loss drugs. In his newsletter from April 28, 2026, he downplayed muscle loss from GLP-1s and argued they don’t significantly impact strength.
“One of the biggest concerns people have about GLP-1 medications like Ozempic, Wegovy, and Mounjaro is muscle loss. Body scans show people losing “lean mass” alongside fat, and that’s triggered fears of weakness and frailty. New research suggests the reality is more complicated and much less alarming.”
Having won the Mr. Olympia seven times, Arnold Schwarzenegger remains one of the most successful bodybuilders in the sport. While it’s been decades since he competed, “The Austrian Oak” uses his platform to offer lifters and gym enthusiasts tips.
At 78, fat doesn’t melt off his physique as it did during his Olympia reign. However, Schwarzenegger still aims to stay athletic, so paying close attention to diet and exercise comes with the territory. Of late, GLP-1 drugs have grown in popularity, with many noting their potential for weight loss. They affect blood sugar, appetite, and digestion, leading Schwarzenegger to discuss how they’ve changed the fitness landscape.
Arnold Schwarzenegger Reveals Muscle Loss from GLP-1s ‘Normal,’ Says Strength ‘Remains Stable’
In Arnold’s Pump Club newsletter, Schwarzenegger revealed that it’s normal to lose muscle on GLP-1 medications. However, he noted that strength levels remain stable.
“According to new research, GLP-1 medications cause modest — and normal — muscle loss, but strength appears to remain stable, and fat loss dramatically outpaces any muscle loss.”
In animal studies, GLP-1 medications reduced body weight by up to 35% over 2-4 weeks. In particular, muscle mass dropped by a modest 5-10%, whereas fat plunged to 41-73%.
“A study published last month tested multiple GLP-1 drugs in obese mice and a pilot trial with 10 patients. We don’t usually focus on animal trials, but because there was a human aspect too, the results are worth your attention.”
“In mice, the medications reduced body weight by 22-35% over 2-4 weeks. Absolute muscle mass dropped only 5-10%, but fat mass plummeted 41-73%.”
Meanwhile, human trials showed that over 12 weeks, fat made up 70% of weight loss, with lean mass coming in at 30%.
“The human trial followed 10 patients with obesity and diabetes on semaglutide for 12 weeks. Fat contributed 70% to weight loss, lean body mass 30%. This is consistent with what you typically see in non-GLP-1 studies with weight loss of 20 pounds or more.”
“The researchers also discovered something overlooked: body composition scans measure “lean mass,” which includes organs like the liver, not just muscle. In this study, the liver shrank more than muscle did, particularly as fatty liver resolved. That means the “muscle loss” numbers commonly cited may overstate what’s actually happening to skeletal muscle because they include changes in the liver.”
Schwarzenegger pointed out that these medications aren’t just suppressing appetite, but changing how muscle adapts to weight loss:
“And an analysis of proteins in the body revealed GLP-1 medications increased mitochondrial proteins in muscle and altered metabolism differently than simple calorie restriction, suggesting these drugs aren’t just suppressing appetite — they may be changing how muscle adapts to weight loss.
The human trial was small and short (10 people, 12 weeks), so this isn’t the final word. But it adds to evidence from larger trials suggesting that muscle loss isn’t alarming and that functional capacity often improves as fat drops.”
Since these medications can decrease lean muscle mass, the bodybuilding legend highlighted that strength training is necessary to support the body throughout a weight-loss phase.
“The real lesson: If you’re using GLP-1 medications — or losing a lot of weight by any method — strength training isn’t optional. You need to build strength and eat enough protein to support the changes occurring in your body.
But the idea that these drugs cause dangerous muscle wasting appears exaggerated. The muscle-to-bodyweight ratio may actually improve, making movement easier as excess fat disappears.”
In addition to Schwarzenegger, 1990s legend Lee Priest has shared his thoughts on GLP-1 drugs. He believes they should only be used for those who are morbidly obese. If weight loss is the primary goal, he explained that exercise and dieting are the more fulfilling options.
GLP-1s have true merit, especially for those struggling with weight gain. Schwarzenegger deems it a tool that should always be coupled with resistance training.
RELATED: Tracy Morgan Credits Ozempic For Recent Weight Loss: “It Cuts My Appetite In Half”
